🤖 feat: add MCP server support by ibetitsmike · Pull Request #35 · coder/coder-k8s

ibetitsmike · 2026-02-10T13:59:26Z

Summary

Add an in-cluster MCP (Model Context Protocol) server mode to coder-k8s so remote clients can inspect operator-managed resources over HTTP (ideal for kubectl port-forward).

New app mode:

--app=mcp-http: MCP over Streamable HTTP on :8090

Background

The operator is expected to run in-cluster, and clients will connect remotely over HTTP (for example via kubectl port-forward svc/coder-k8s -n coder-system 8090:8090).

Implementation

New package internal/app/mcpapp using github.com/modelcontextprotocol/go-sdk/mcp
- Streamable MCP endpoint: /mcp
- Probes: /healthz, /readyz
- Idle Streamable HTTP sessions expire after 15 minutes to reclaim abandoned sessions.
- Kubernetes clients:
  - controller-runtime client (for Coder CRDs + aggregated API types)
  - client-go clientset (for events + pod logs)
Tool safety bounds:
- get_events requires a namespace and is paginated (default limit 200, max 1000, returns a continue token).
- get_pod_logs applies safe defaults/bounds and marks output with (truncated) when the byte cap is hit.
app_dispatch.go supports mcp-http and is covered by dispatch tests.
Deployment + docs:
- deploy/mcp-deployment.yaml (Deployment: coder-k8s-mcp)
- deploy/mcp-service.yaml (Service: coder-k8s, port 8090)
- deploy/rbac.yaml (adds coder-k8s-mcp SA + read-only ClusterRole)
- docs/how-to/mcp-server.md

MCP tools (MVP)

list_control_planes
get_control_plane_status
list_workspaces
list_templates
get_events
get_pod_logs
check_health

Validation

make verify-vendor
make build
make test
make lint

Risks

HTTP mode does not add auth on its own (intended for in-cluster + port-forward usage).
RBAC grants read access to pods/log, events, namespaces, and Coder CRDs for the MCP service account.

Generated with mux • Model: openai:gpt-5.2 • Thinking: xhigh • Cost: $3.92

https://mux.md/1B5WD#6zoglyfH45bqAQ

ibetitsmike · 2026-02-10T13:59:35Z

@codex review

Please review for:

MCP server app mode dispatch (mcp-stdio, mcp-http)
Tool handlers correctness and error handling
RBAC scope (read-only) and deploy manifest consistency

ibetitsmike · 2026-02-10T14:02:22Z

@codex review

Pushed a small follow-up to fix docs-quality (cspell) for health endpoints.

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ibetitsmike · 2026-02-10T14:11:50Z

@codex review

Update: removed mcp-stdio; MCP is now HTTP-only (--app=mcp-http). PR description updated accordingly.

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ibetitsmike · 2026-02-10T14:19:20Z

@codex review

Addressed the P1 feedback on get_pod_logs (bounded read + safe defaults) and resolved the review thread.

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ibetitsmike · 2026-02-10T14:25:55Z

@codex review

Applied fixes for:

Streamable HTTP session timeout (idle sessions now expire)
get_pod_logs bounded output (tailLines default + byte cap)

Resolved the previous review threads.

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ibetitsmike · 2026-02-10T14:36:45Z

@codex review

Addressed feedback:

get_events now requires a namespace and is paginated/bounded (default limit + continuation).

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ibetitsmike · 2026-02-10T14:47:26Z

@codex review

Follow-up: adjusted get_pod_logs truncation detection (no apiserver LimitBytes; local cap + marker).

chatgpt-codex-connector · 2026-02-10T14:53:21Z

Codex Review: Didn't find any major issues. Already looking forward to the next diff.

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chatgpt-codex-connector · 2026-02-10T14:53:58Z

Codex Review: Didn't find any major issues. Another round soon, please!

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chatgpt-codex-connector · 2026-02-10T14:54:59Z

Codex Review: Didn't find any major issues. 👍

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🤖 feat: add MCP server support

c6889f2

🤖 fix: ignore healthz/readyz for cspell

039ab0b

chatgpt-codex-connector Bot reviewed Feb 10, 2026

View reviewed changes

Comment thread internal/app/mcpapp/tools.go Outdated

🤖 refactor: remove mcp-stdio mode

fa6e7b9

chatgpt-codex-connector Bot reviewed Feb 10, 2026

View reviewed changes

Comment thread internal/app/mcpapp/http.go Outdated

Comment thread internal/app/mcpapp/tools.go Outdated

🤖 fix: bound get_pod_logs output

f35420c

🤖 fix: expire idle MCP HTTP sessions

d88c856

chatgpt-codex-connector Bot reviewed Feb 10, 2026

View reviewed changes

Comment thread internal/app/mcpapp/http.go Outdated

chatgpt-codex-connector Bot reviewed Feb 10, 2026

View reviewed changes

Comment thread internal/app/mcpapp/tools.go

🤖 fix: paginate get_events output

252a378

chatgpt-codex-connector Bot reviewed Feb 10, 2026

View reviewed changes

Comment thread internal/app/mcpapp/tools.go Outdated

🤖 fix: detect pod log truncation

a2c2339

ibetitsmike added this pull request to the merge queue Feb 10, 2026

Merged via the queue into main with commit 5fd5ba9 Feb 10, 2026
11 checks passed

ibetitsmike deleted the mike/mcp-server branch February 10, 2026 15:12

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Summary

Background

Implementation

MCP tools (MVP)

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